Dear wise members of the list. I am (still) trying to implement a control panel feature for the U2A USB sound card. I (finally!) have the alsa patch from Clemens Ladisch up and running - at least I can compile a small program that when run squirts of a small control transfer URB to the sound card without complaints. Now, half of the URBs sent to the device are CONTROL_TRANSFER blocks, but the other half are marked as CLASS_INTERFACE in the SnoopyPro logs. See a typical example below. I have googled the net and searched the USB specs without getting much wiser as to what a CLASS_INTERFACE request is and does. Can I send it using CONTROL_TRANSFER URBs or is yet another extension of the alsa driver necessary ? Cheers -- Jan Holst 277 out down n/a 710.461 CLASS_INTERFACE 01 URB Header (length: 80) SequenceNumber: 277 Function: 001b (CLASS_INTERFACE) PipeHandle: 00000001 SetupPacket: 0000: 00 01 00 01 00 04 ea 87 bmRequestType: 00 DIR: Host-To-Device TYPE: Standard RECIPIENT: Device bRequest: 01 CLEAR_FEATURE TransferBuffer: 0x00000001 (1) length 0000: 01 277 out up n/a 710.471 CONTROL_TRANSFER - 0x00000000 URB Header (length: 80) SequenceNumber: 277 Function: 0008 (CONTROL_TRANSFER) PipeHandle: 860fee14 SetupPacket: 0000: 21 01 00 01 00 04 01 00 bmRequestType: 21 DIR: Host-To-Device TYPE: Class RECIPIENT: Interface bRequest: 01 No TransferBuffer __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com